fixup! Port MultiBackendJobManager to DummyBackend fixtures

Author: soxofaan

tests/extra/test_job_management.py

@@ -317,7 +317,7 @@ def test_manager_must_exit_when_all_jobs_done(self, tmp_path, requests_mock, sle
 
         Cause was that the run_jobs had an infinite loop when jobs ended with status error.
         """
-        # TODO: port to job_manager fixture
+        # TODO: port to job_manager and DummyBackend fixtures
 
         requests_mock.get("http://foo.test/", json={"api_version": "1.1.0"})
         requests_mock.get("http://bar.test/", json={"api_version": "1.1.0"})